Supply circuit for a heat exchange medium for a consumer, industrial plant and method for operating them

ABSTRACT

A supply circuit for a heat exchange medium for a consumer having an inflow line for the heat exchange medium and a return line for the heat exchange medium, the lines being connected to one another by way of a consumer heat exchanger. A pumping device for conveying the heat exchange medium through the supply circuit is a frequency-controlled pumping device having a conveying pump and a frequency converter which is assigned to the conveying pump. For an industrial plant, a primary circuit is connected to a supply circuit of this type as a secondary circuit. In either case, the supply circuit is operated selectively in one of two operating modes. In a first operating mode, the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of an admixture control operation in which the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of an actuation of the valve. In a second operating mode, the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by a volumetric flow control operation, by the frequency converter of the pumping device being actuated.

RELATED APPLICATIONS

The present application claims priority to German Patent Application No. 10 2017 116 079.5 filed Jul. 18, 2017, the contents of which are fully incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a supply circuit for a heat exchange medium for a consumer having

-   -   a) an inflow line for the heat exchange medium and a return line         for the heat exchange medium, which lines are connected to one         another by way of a consumer heat exchanger;     -   b) a pumping device for conveying the heat exchange medium         through the supply circuit.

Moreover, the invention relates to an industrial plant having a primary circuit for a heat exchange medium, which primary circuit is connected to at least one secondary circuit for the heat exchange medium for a consumer, an inflow line of the secondary circuit being connected to an inflow line of the primary circuit, and a return line of the secondary circuit being connected to a return line of the primary circuit, and to a method for operating a supply circuit or an industrial plant.

BACKGROUND OF THE INVENTION

In industrial plants, there are distributing sections for a heat exchange medium in a known way, which distributing sections form a primary circuit for the heat exchange medium, by means of which thermal energy can be transferred to consumers with the aid of consumer heat exchangers there. In a manner which is dependent on the direction of the heat transfer, the heat exchange medium can be utilized for a cooling operation or a heating operation. As a rule, the heat exchange medium is water, and another frequently utilized heat exchange medium is, for example, glycol or a mixture of water and glycol.

In the case of known supply circuits, the pumping device provides a constant and unchanging volumetric flow of the heat exchange medium through the consumer or through its consumer heat exchanger, and what is known as an admixture control operation takes place, by the inflow line being fed firstly from the primary circuit and secondly from the return line. In this case, a certain minimum pressure has to always be ensured in the primary circuit, to which end one or more network pumps are provided in the primary circuit, which network pumps signify a comparatively high maintenance effort.

In addition, in every operating state, said supply circuits require largely the same energy, without a change in the requirement of thermal energy at the consumer, for example in the case of heating operations, resulting in a reduced energy requirement of the supply circuit.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a supply circuit and a method for operating a supply circuit of the type mentioned at the outset, which supply circuit and method allow an improved energy footprint.

This object may be achieved in the case of a supply circuit of the type mentioned at the outset by virtue of the fact that

-   -   c) the pumping device is a frequency-controlled pumping device         having at least one conveying pump and a frequency converter         which is assigned to the conveying pump.

The use of a frequency-controlled pumping device opens up modes of operation which have not been possible up to now and in the case of which the energy requirement for the operation of the supply circuit can be correlated with the energy requirement at the consumer. In particular, the conveying capacity of the conveying pump can be varied, as a result of which the volumetric flow of the heat exchange medium through the consumer heat exchanger can be adapted to the requirement there.

It is advantageous if the inflow line and the return line are connected to one another by way of a circulation line in such a way that heat exchange medium can be guided out of the return line in the circuit into the inflow line. In this way, the heat exchange medium can be utilized again, without being guided back, for example, directly into the above-described primary circuit again.

It is favorable here if there is a valve, by means of which the proportion of the heat exchange medium which flows through the circulation line into the inflow line can be set.

Although said valve can also be arranged in the return line, it is advantageous in terms of flow if the valve is arranged in the circulation line.

It is advantageous, moreover, if the circulation line opens into the inflow line upstream of the conveying pump. The heat exchange medium which flows out of the circulation line into the inflow line is thus conveyed effectively by the conveying pump, and at the same time satisfactory thorough mixing of the heat exchange medium which is already situated in the inflow line with the heat exchange medium from the circulation line is ensured.

The frequency-controlled pumping device and/or the valve can preferably be actuated by means of a control device.

An effective adaptation of the operating modes of the supply circuit in a manner which is dependent on the requirement at the consumer can take place, in particular, when the control device is connected to a sensor system, by means of which the inlet pressure of the heat exchange medium on the inlet side of the conveying pump and/or the outlet pressure of the heat exchange medium on the outlet side of the conveying pump and/or the temperature of the heat exchange medium in the inflow line on the inlet side of the consumer heat exchanger and/or the temperature of the heat exchange medium in the return line on the outlet side of the consumer heat exchanger can be detected, and the associated sensor responses can be transmitted to the control device.

In order that the control device can detect the effect of the control operations, it is favorable if the control device can be connected to a consumer sensor system, by means of which at least one operating parameter of the consumer can be detected and can be transmitted to the control device.

The abovementioned object is achieved in the case of an industrial plant of the type mentioned at the outset by virtue of the fact that the secondary circuit is a supply circuit having some or all of the above-described features.

In the case of a supply circuit having a frequency-controlled pumping device and a valve controller for the circulation line, the abovementioned object may be achieved by virtue of the fact that the supply line is operated selectively in one of two operating modes,

-   -   a) in a first operating mode, the temperature of the heat         exchange medium which enters into the consumer heat exchanger         from the inflow line being set by way of an admixture control         operation, in the case of which the temperature of the heat         exchange medium which enters into the consumer heat exchanger         from the inflow line is set by way of an actuation of the valve;     -   b) in a second operating mode, the temperature of the heat         exchange medium which enters into the consumer heat exchanger         from the inflow line being set by way of a volumetric flow         control operation, by the frequency converter of the pumping         device being actuated.

In addition, it is favorable if, in a third operating mode, the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of a combination control operation, in the case of which the admixture control operation and the volumetric flow operation are combined with one another.

Other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings an the detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, exemplary embodiments of the invention will be described in greater detail using the drawings, in which:

FIG. 1 shows a diagrammatic layout of an industrial plant, and

FIG. 1A shows a partial modification of the industrial plant in accordance with FIG. 1.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

While this invention is susceptible to embodiments in many different forms, there is described in detail herein, preferred embodiments of the invention with the understanding that the present disclosures are to be considered as exemplifications of the principles of the invention and are not intended to limit the broad aspects of the invention to the embodiments illustrated.

In FIG. 1, 10 denotes an industrial plant, in the case of which a heat exchange medium 12 is guided in a primary circuit 14, which heat exchange medium 12 is called an HT medium 12 (“Heat Transfer Medium”) 12 in the following text. The HT medium 12 is made available to one or more consumers 16 which is/are connected via a respective secondary circuit 18 to the primary circuit 14. FIG. 1 shows only a single consumer 16 in a secondary circuit 18 for the sake of clarity. The flow direction of the HT medium 12 in the primary circuit 14 and the secondary circuit 18 is illustrated by way of respective arrows which are not labeled specifically. A secondary circuit 18 of this type generally defines a supply circuit for a consumer 16.

In the following text, the terms “primary circuit” and “secondary circuit” are shortened using “PC” (“Primary Circuit”) and “SC” (“Secondary Circuit”), respectively, as long as they are used as prefixes in the designation of parts and components, in order to indicate them as belonging to the primary circuit 14 or to the secondary circuit 18.

Depending on the application, the HT medium 12 can be a heating medium or a cooling medium. The invention will be described using exemplary embodiments, in the case of which the HT medium 12 is water which is utilized as a heating medium.

The primary circuit 14 comprises a PC inflow line 20, into which hot HT medium 12 in the form of hot water 22 is fed at an inlet 24. The PC inflow line 20 merges into a PC return line 26, from which cold HT medium 12 in the form of cold water 28 exits at an outlet 30. The terms “hot” and “cold” show merely the relative temperatures of the media in comparison; hot HT medium 12 is warmer than cold HT medium 12.

On the path from the outlet 30 to the inlet 24, the HT medium 12 is conditioned and, in particular, is heated or cooled again, in order subsequently to be fed as heating or cooling medium into the PC inflow line 20 again.

The PC inflow line 20 and the PC return line 26 are decoupled from one another in a manner known per se via an equalizing device 32, in order to equalize circulation flows of different magnitude in the PC inflow line 20 and the PC return line 26. A hydraulic separator 34 is provided for this purpose.

In the case of an alternative arrangement which is illustrated by part FIG. 1A, a plate heat exchanger 36 is provided instead of the hydraulic separator 34, the PC inflow line 20 and the PC return line 26 being connected to one another in the plate heat exchanger 36 by way of a PC heat exchanger line 38 to form a circuit line which then defines the primary circuit 14. The plate heat exchanger 36 is fed a separate heat exchange medium 40 in a separate temperature control circuit 42, with the result that the HT medium 12 in the primary circuit 14 can be temperature controlled, that is to say heated or cooled, by way of the separate heat exchange medium 40.

In this case, for example, glycol or a mixture of water and glycol can then be used as HT heat exchange medium 12 in the primary circuit 14.

Dashed reference lines which can be seen in FIG. 1A relate to an exemplary embodiment which is not shown specifically and will be described further below.

As an example for a consumer 16 in the secondary circuit 18, FIG. 1 shows a consumer heat exchanger 44 which can be configured, in particular, as a finned heat exchanger or plate heat exchanger known per se. Said consumer heat exchanger 44 can be enclosed for its part, for example, by a circulation system, in order to temperature control air which accrues there and has to be conditioned.

The secondary circuit 18 comprises an SC inflow line 46 which leads from the PC inflow line 20 to the consumer heat exchanger 44. There, the secondary inflow line 46 merges into an SC heat exchanger line 48 which leads through the consumer heat exchanger 44 and subsequently opens into an SC return line 50 which is connected to the PC return line 26.

The SC inflow line 46 and the SC return line 50 are connected to one another by way of an SC circulation line 52 in such a way that HT medium 12 can be guided from the SC return line 50 in the circuit into the SC inflow line 46 again. Said return takes place before the HT medium 12 flows back into the PC return line 26. A valve 54 is arranged in the SC circulation line 52, with the result that the proportion of HT medium 12 to be guided back, that is to say the proportion of HT medium 12 which flows out of the SC circulation line 52 into the inflow line 46, can be set. The valve 54 is operated by means of a valve drive 56.

The secondary circuit 18 comprises a frequency-controlled pumping device 58 having a conveying pump 60 for the HT medium 12 and an associated frequency converter 62. In the case of the present exemplary embodiment, the conveying pump 60 is arranged between the SC circulation line 52 and the consumer heat exchanger 44 in the SC inflow line 46. In other words, the SC circulation line 52 opens into the SC inflow line 46 upstream of the pumping device 58 or the conveying pump 60.

The valve drive 56 of the valve 54 and the frequency converter 62 of the conveying pump 60 are actuated by means of a control device 64 which is connected to this end via control lines 66 and 68 to the valve drive 56 and the frequency converter 62. The control device 64 controls the valve 56 and the conveying pump 60 in a manner which is dependent on measured parameters which it obtains from an SC sensor system 70 which belongs to the secondary circuit 18 and transmits associated sensor responses to the control device 64. The SC sensor system 70 comprises a plurality of sensors which transmit their sensor data to the control device 64, which is indicated by way of dashed connecting lines which are not provided specifically with a designation. A communication of this type can take place via corresponding data lines or in a wireless manner.

Upstream of the conveying pump 60, an inlet pressure sensor 72 measures the inlet pressure of the HT medium 12 on the inlet side of the conveying pump 60. An outlet pressure sensor 74 measures the outlet pressure of the HT medium 12 on the outlet side of the conveying pump 60. In this way, the possibility for a differential pressure measurement is integrated into the pumping device 58.

Moreover, the SC sensor system 70 comprises an inflow temperature sensor 76 which detects the temperature of the HT medium 12 in the SC inflow line 46 on the inlet side of the consumer 16, that is to say on the inlet side of the consumer heat exchanger 44 in the present case. A return temperature sensor 78 determines the temperature of the HT medium 12 in the SC return line 50 on the outlet side of the consumer 16, that is to say on the outlet side of the consumer heat exchanger 44 in the present case.

In addition, a consumer sensor system 80 provides the control device 64 with feedback about operating parameters of the consumer 16 which reflect the achieved effect of the settings in the secondary circuit 18 on the consumer. In the present case, the consumer sensor system 80 is exemplified using a temperature sensor 82.

If, for example, the consumer heat exchanger 44 belongs to a circulation system as mentioned above, the temperature sensor 82 of the can be arranged in the air flow of the circulation system, which air flow has left the consumer heat exchanger 44.

A particularly energy-efficient operation of the secondary circuit 18 for the transfer of heat at the consumer 16 is possible by way of the frequency-controlled pumping device 58:

In a first operating mode, the temperature of the HT medium 12 which enters into the consumer heat exchanger 44 from the SC inflow line 46 can be set by way of an admixture control operation. Here, the volumetric flow of the HT medium 12 is kept constant by way of the consumer heat exchanger 44, and the control operation takes place via an actuation of the valve 54 in the SC circulation line 52. If, for example, the temperature sensor 82 detects that the circulating air to be temperature controlled is too hot, that therefore the temperature of the circulating air is above a setpoint temperature, and if the return temperature sensor 78 detects that the temperature of the HT medium 12 in the SC return line 50 is lower than the setpoint temperature of the circulating air, the temperature of the HT medium 12 in the SC inflow line 46 can be lowered, by the valve 54 being opened or being opened further, with the result that HT medium 12 from the SC return line flows over into the SC inflow line and cools the HT medium 12 which is situated there overall to a lower temperature than without said flowing over of HT medium 12.

The volumetric flow of the HT medium 12 in the SC inflow line 46 is kept constant by way of a corresponding control operation of the conveying pump 60.

If, in contrast, the circulating air to be temperature controlled is too cold, the valve 54 can be closed, with the result that unmixed hot HT medium 12 is fed from the PC inflow line 20 to the consumer heat exchanger 44, as a result of which the circulating air to be temperature controlled is heated.

In a second operating mode, the temperature of the HT medium 12 which enters into the consumer heat exchanger 44 from the SC inflow line 46 can be set by way of a volumetric flow control operation. Here, the valve 54 is closed or remains open in a position, and the feeding of the HT medium 12 from the PC inflow line 20 is controlled only via the rotational speed of the conveying pump 60. If the valve 54 is closed, the HT medium 12 which is fed into the consumer heat exchanger 44 is hot, unmixed HT medium 12 from the PC inflow line 20.

In a third operating mode, the setting of the temperature of the HT medium 12 which enters into the consumer heat exchanger 44 from the SC inflow line 46 takes place by way of a combination control operation which combines the above-described admixture control operation and the above-described volumetric flow control operation.

If the temperature of the circulating air to be temperature controlled is to be lowered, only the rotational speed of the conveying pump 60 can first of all be reduced here as far as a lower threshold value without a change in the setting of the valve 54, which lower threshold value lies, for example, at 50% of the maximum rotational speed of the conveying pump 60. When said threshold value is reached, the volumetric flow is kept constant and the further temperature control operation takes place by way of a corresponding actuation of the valve 54.

With the aid of the frequency-controlled pumping device 58, pressure changes in the primary circuit 14 which can occur as a result of further consumers 16 in further secondary circuits 18 can also be compensated for rapidly and reliably.

Moreover, the control device 64 is set up in such a way that it is capable of detecting the energy which is required for the operation. The pump characteristic curve of the conveying pump 60 is stored in the frequency converter 62. By way of a corresponding current measurement in conjunction with the rotational speed of the conveying pump 60 and the result of the differential pressure measurement by way of the pressure sensors 72 and 74, the volumetric flow can be calculated and can be output as a 4-20 mA current signal, which in turn can be converted, in interaction with the temperature data of the temperature sensors 76 and 78, into a value which reflects the required energy. In a manner which is dependent on the obtained data, the control device 64 decides which operating mode is the most favorable with regard to the energy consumption and the required effectivity in the case of the temperature control operation at the consumer 16. Further energy meters can be dispensed with in the plant 10.

As a result of the flexibility during the selection of the control principle, that is to say admixture control operation, volumetric flow control operation or combination control operation, the secondary circuit 18 can be operated in an energy-optimized manner and can always be set to the most favorable energy consumption.

Overall, the conveying pump 60 is as a rule operated in all operating modes in such a way that the pressure at the outlet pressure sensor 74 is higher than at the inlet pressure sensor 72, that is to say that the pressure of the HT medium 12 in the SC return line 50 is always greater than in the SC inflow line 46 upstream of the conveying pump 60 and in the consumer heat exchanger 44 or in the consumer heat exchanger line 48.

In addition, no blanket pressure has to be maintained in the PC inflow line 20 of the primary circuit 14; no network pumps are necessary in the primary circuit 14, as a result of which, in addition to the improved energy footprint, the maintenance and servicing effort of the plant also decreases.

In the case of a modification which is not shown specifically, the consumer heat exchanger 44 can also be configured as a plate heat exchanger. This is considered, in particular, in the case of the variant in accordance with FIG. 1A if glycol is utilized as HT medium 12 in the primary circuit 14.

In the case of a further modification which is not shown specifically, the secondary circuit 18 can also be configured as a closed circuit which is decoupled from the primary circuit 14, by a plate heat exchanger 84 being arranged between the primary circuit 14 and the secondary circuit 18. The arrangement at this transition between the primary circuit 14 and the secondary circuit 18 then corresponds approximately to the arrangement which part FIG. 1A illustrates, where the lines and components which are relevant for said exemplary embodiment are provided with the abovementioned dashed reference lines.

The temperature control circuit 42 there then corresponds to a feed circuit 86, in the case of which a feed inflow line 20 a branches off from the PC inflow line 20, and a feed return line 26 a leads to the PC return line 26, the feed inflow line 20 a and the feed return line 26 a being connected in the plate heat exchanger 84 by way of a heat exchanger line 88.

In this case, the SC inflow line 46 and the SC return line 50 are connected to one another in the heat exchanger 84 by way of a further heat exchanger line which is denoted by 90.

In this case, for example, glycol or a mixture of water and glycol can then be used as HT heat exchange medium 12 in the secondary circuit, whereas the primary circuit 14 can conduct water as heat exchange medium.

In the case of this variant, the control operation of the plate heat exchanger 84 can likewise take place by way of the control device 64 which ensures an equalization in terms of energy, in order to achieve an energy-optimized mode of operation.

While in the foregoing there has been set forth preferred embodiments of the invention, it is to be understood that the present invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. While specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the characteristics of the invention and the scope of protection is only limited by the scope of the accompanying claims. 

What is claimed is:
 1. A supply circuit for a heat exchange medium for a consumer comprising: a) an inflow line for a heat exchange medium and a return line for the heat exchange medium, the lines being connected to one another by way of a consumer heat exchanger; b) a pumping device for conveying the heat exchange medium through the supply circuit, wherein c) the pumping device is a frequency-controlled pumping device with a conveying pump and a frequency converter which is assigned to the conveying pump.
 2. The supply circuit according to claim 1, whrein the inflow line and the return line are connected to one another by way of a circulation line in such a way that heat exchange medium can be guided out of the return line in the supply circuit into the inflow line.
 3. The supply circuit according to claim 2, wherein there is a valve, by means of which the proportion of the heat exchange medium which flows through the circulation line into the inflow line can be set.
 4. The supply circuit according to claim 3, wherein the valve is arranged in the circulation line.
 5. The supply circuit according to claim 2, wherein the circulation line opens into the inflow line upstream of the conveying pump.
 6. The supply circuit according to claim 3, wherein the frequency-controlled pumping device and/or the valve can be actuated by means of a control device.
 7. The supply circuit according to claim 6, wherein the control device is connected to a sensor system, by means of which an inlet pressure of the heat exchange medium on an inlet side of the conveying pump and/or an outlet pressure of the heat exchange medium on an outlet side of the conveying pump and/or a temperature of the heat exchange medium in the inflow line on an inlet side of the consumer heat exchanger and/or the temperature of the heat exchange medium in the return line on an outlet side of the consumer heat exchanger can be detected, and associated sensor responses can be transmitted to the control device.
 8. The supply circuit according to claim 6, wherein the control device is connected to a consumer sensor system, by means of which at least one operating parameter of a consumer can be detected and can be transmitted to the control device.
 9. An industrial plant comprising a primary circuit for a heat exchange medium, the primary circuit being connected to at least one secondary circuit for the heat exchange medium for a consumer, an inflow line of the secondary circuit being connected to an inflow line of the primary circuit, and a return line of the secondary circuit being connected to a return line of the primary circuit, wherein the secondary circuit is a supply circuit according to claim
 1. 10. A method for operating a supply circuit comprising: a) selecting one of two operating modes to operate a supply circuit, the supply circuit comprising the supply circuit of claim 3, wherein aa) in a first operating mode, a temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of an admixture control operation, in the case of which the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of an actuation of the valve; ab) in a second operating mode, the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of a volumetric flow control operation by the frequency converter of the pumping device.
 11. The method according to claim 10, wherein in a third operating mode, the temperature of the heat exchange medium which enters into the consumer heat exchanger from the inflow line is set by way of a combination control operation, in the case of which the admixture control operation and the volumetric flow control operation are combined with one another. 